title: Helical tomotherapy planning for lung cancer based on ventilation magnetic resonance imaging.
abstract: To investigate the feasibility of lung ventilation-based treatment planning, computed tomography and hyperpolarized (HP) helium-3 (He-3) magnetic resonance imaging (MRI) ventilation images of 6 subjects were coregistered for intensity-modulated radiation therapy planning in Tomotherapy. Highly-functional lungs (HFL) and less-functional lungs (LFL) were contoured based on their ventilation image intensities, and a cylindrical planning-target-volume was simulated at locations adjacent to both HFL and LFL. Annals of an anatomy-based plan (Plan 1) and a ventilation-based plan (Plan 2) were generated. The following dosimetric parameters were determined and compared between the 2 plans: percentage of total/HFL volume receiving ≥20 Gy, 15 Gy, 10 Gy, and 5 Gy (TLV(20), HFLV(20), TLV(15), HFLV(15), TLV(10), HFLV(10), TLV(5), HFLV(5)), mean total/HFL dose (MTLD/HFLD), maximum doses to all organs at risk (OARs), and target dose conformality. Compared with Plan 1, Plan 2 reduced mean HFLD (mean reduction, 0.8 Gy), MTLD (mean reduction, 0.6 Gy), HFLV(20) (mean reduction, 1.9%), TLV(20) (mean reduction, 1.5%), TLV(15) (mean reduction, 1.7%), and TLV(10) (mean reduction, 2.1%). P-values of the above comparisons are less than 0.05 using the Wilcoxon signed rank test. For HFLV(15), HFLV(10), TLV(5), and HTLV(5), Plan 2 resulted in lower values than plan 1 but the differences are not significant (P-value range, 0.063-0.219). Plan 2 did not significantly change maximum doses to OARs (P-value range, 0.063-0.563) and target conformality (P = 1.000). HP He-3 MRI of patients with lung disease shows a highly heterogeneous ventilation capacity that can be utilized for functional treatment planning. Moderate but statistically significant improvements in sparing functional lungs were achieved using helical tomotherapy plans.
authors.affiliation: Department of Radiation Oncology, University of Virginia, Charlottesville, VA 22908, USA.
authors.forename: Jing
authors.initials: J
authors.lastname: Cai
authors.forename: Robert
authors.initials: R
authors.lastname: McLawhorn
authors.forename: Tallisa A
authors.initials: TA
authors.lastname: Altes
authors.forename: Eduard
authors.initials: E
authors.lastname: de Lange
authors.forename: Paul W
authors.initials: PW
authors.lastname: Read
authors.forename: James M
authors.initials: JM
authors.lastname: Larner
authors.forename: Stanley H
authors.initials: SH
authors.lastname: Benedict
authors.forename: Ke
authors.initials: K
authors.lastname: Sheng
mesh_terms: D000368:Aged; D005240:Feasibility Studies; D005260:Female; D006371:Helium; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D019047:Phantoms, Imaging; D011874:Radiometry; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D012119:Respiration; D036542:Tomography, Spiral Computed; D016896:Treatment Outcome
chemical_list: D006371:Helium